function s1_generate_a_series_of_files(){
   for index in $(seq 1 100);do
  echo $index > "/tmp/new_file$index"
done
}

function s2_list_4_files_in_long_format_about_account_and_group(){
   files=("/etc/passwd" "/etc/group" "/etc/shadow" "/etc/gshadow")
   for file in "${files[@]}";do
       ls -l "$file"
   done | sort
}

function s3_find_items_related_to_given_username(){
   grep -h $1 /etc/{passwd,shadow} |sort -d
}

function s4_find_items_related_to_given_group_name(){
  grep -h $1 /etc/{group,gshadow} |sort -d
}

function s5_create_groups_for_given_group_names(){
   local groups=("rnd" "itoperation")
   for group in "${groups[@]}";do
         groupadd "$group"
done
}

function s6_create_users_and_set_their_group_as_required(){
users=("adam" "bob" "calvin" "david" "edward")
primary=("users" "users" "users" "users" "users")
supplementary=("rnd" "rnd" "itoperation" "itoperation" "rnd")
for i in "${!users[@]}";do
useradd -g "${primary[$i]}" "${users[$i]}"
usermod -aG "${supplementary[$i]}" "${users[$i]}"
done
}

function s7_change_users_shell(){
users=("adam" "edward")
for user in "${users[@]}";do
  usermod -s /usr/bin/sh "$user"
done
}

function s8_set_password_change_policy(){
sudo chage -m 10 -M 60 -W 10 adam
sudo chage -m 10 -M 60 -W 10 bob
sudo chage -m 10 -M 60 -W 10 calvin
sudo chage -m 10 -M 60 -W 10 david
sudo chage -m 10 -M 60 -W 10 edward
}

function s9_set_password_for_five_users(){
username=(adam bob calvin david edward)
for i in $(seq 1 5);do
echo ${!i}
echo $(($i-1))
done
echo "${username[0]}:$1" | chpasswd
echo "${username[1]}:$2" | chpasswd
echo "${username[2]}:$3" | chpasswd
echo "${username[3]};$4" | chpasswd
echo "${username[$(($i-1))]}:$5" | chpasswd
}

function s10_lock_bobs_password(){
 passwd -l bob
}

function s11_include_adam_into_wheel_group(){
 usermod -a -G wheel adam
}
function s12_change_files_permission(){
for i in {1..33};do chmod -R 640 /tmp/new_file$[3*i];done
}
